Printing plate and method of making the same



March 15, 1932. .1L-r. slMMs E'r Al. 1,849,598

' PRINTING PLATE AND METHOD 0F MAKNG THE SAME Filed Nov. 26,` 1928Pateiited Mar. 15, 1932 UNITED STATES .PATENT OFFICE JAMES T. SIMMS ANDGEORGE A. SIMMS, 0F CHICAGO, ILLINOIS, ASSIGNORS, BY MESNE ASSIGNMENTS,TO BURTON R. HERRING, OF CHICAGO, ILLINOIS PRINTING PLATE AND METHOD OFMAKING TILE Application led November 26,v 1928. Serial No. 321,817.

Our invention which relates to a printing plate and a method ofproducing the same, is concerned more particularly with a treatmentapplied to the impression surface of such a plate by which it isrendered suitable for printing with water-soluble inks. In accomplishingthis end, we preserve all the sharpness of definition and accuracy ofthe Well-known printing plates, such as commonly use oil-soluble inks. p

It is a primary object of this invention to produce a printing plate ofthe character described by mechanical means with a minimum of operationsand expense. The term printing plate, as used herein, will includeoriginal zinc or copper etchings executed either by hand or bywell-known processes; electrotypes or steel-faced plates produced and/ortreated by any of the processes which enhance durability of the originalplate or duplicates thereof; and linoleum or composition plates, otherthan rubber, which are cut by hand or machine. It is to printing platesanswering generally to the preceding de` scription, that the presenttreatment may be applied. y

According to our invention, a thin sheet of india rubber is applied overand adhered to.

the impression surface of a printing plate. By the term india rubber, werefer to suit able mixtures having a aoutchouc base, it being arequirement that such mixture when vulcanized will present a surfaceover which eitherv water, oil, and/or alcohol soluble inks may bedistributed in a manner suitable for printing purposes. A rubber facingadaptable for this process may have a thickness of .006 to .025 inches.Heavier facings may be used, but only for purposes where a fine resultis not essential, 'such as in the prepara'- tion of linoleum orcomposition plates to be employed for printing boxes and other grosserwork. A material known as gutta percha may be used in certain cases.

A printing plate having its impression surface covered with such afacing which is adhered to the plate at every point is adapted admirablyfor printing with water-soluble inks: It will endure through a.prolonged service, and will seldom require renewal or replacement. The,process of applying the facing to the plate is performed mechanically soas tov ensure uniform and accurate results in every case.

In the drawings we have illustrated fourl views in which#- Figure 1 is avertical section through the impression assembly as it appears whileundergoing pressure;

Fig. 2 is a fragmentary enlarged-section through the impressionassembly;

Fig. 3 is a fragmentary enlarged view through the finished plate; and

Fig. 4 which is a view similar to Fig. 3 shows a plate of modified formto which a facing is applied in a slightly different manner.

For purposes of illustration we have shown an original printing plate 10mounted upon the usual base 11 which may be wood, metal, or othermaterial. The plate illustrated in Figs. 1 to 3 is formed with aplurality of vents 12 communicating with depressed portions thereof torelieve .the air trapped therein when the facing material ifspressedtightly against its impression vsurace.

The impression surface of the printing plate is thoroughly cleansed ofgrease and other foreign matter, as by wiping the same with alcohol,benzol or the like. When the plate is dry, a suitable adhesive 13 isapplied to its impression surface. This adhesive may desirably have anasphaltum base.

For some work it may be advisable to remove most of the adhesive fromthe elevations forming the actual printing surfaces which are' impressedagainst the paper. This is done conveniently with a felt wiper wettedwith a suitable solvent for the adhesive elnployed. When the adhesivebecomes tacky the facing material is .applied thereto. In the formshown, this comprises a thin sheet of uncured india rubber 14 which haspreviously been carefully and evenly laid rover a resilient cushion 15.Such a cushion may advantageously consist of laminations suchv as a pileof rubber sheets, the engaging surfaces of which are lubricated at 16 asby dusting with talcum powder or the like.v By this treatment, theseveral laminations are rendered suciently slippery to slide relativelyto each other and to the facing material 14, as required, therebyenabling the latter to conform to every irregularity in the impressionsurface of the printing plate. The resilient cushion is desirably restedupon a smooth metal plate 17, being retained in place thereon by a clamp18, which engages with one edge thereof.

The impression assembly includes the base plate 17, the resilientcushion 15, the sheet of facing material 14, and the printing plate 10Whose impression surface, with adhesive in the tacky stage, is presentedto the facing' material. IThe entire assembly is then placed betweenpressure blocks 19 and 20 of a hydraulic or other suitable press. Inresponse to the pressure delivered by the press to the impressionassembly, the facing material, being the uncured rubber sheet 14, isconformed firmly and intimately over the impression surface of theprinting plate 10, as shown in F ig. 3; and the intervening coating ofadhesive 13 serves during this pressure treatment to unite the facinginseparably and closely to the plate. the resulting product being acontinuous facing 21 (see Fig. 3) conforming exactly to everyirregularity in the impression surface of the printing plate. rlheblocks which bear against the printing plate should be of such materialas to facilitatezthe escape of air which is released through the vents12.

The resilient cushion which underlies the facing material during theinterval that pressure is applied thereto is preferably built up of thinlaminations such as sheets of rubber having a suitable lubricant betweentheir engaging surfaces. With such a. construction the cushion may yieldin the direction of the pressure force which is applied, and also mayslide laterally as required by the stretching of the facing materialduring its adjustment to the irregularities in the impression surface ofthe printing plate. The resultis that the pressure applied against thefacing material during this stage of the operation is directed overevery point, including the depressions as well as the elevations, of theim' pression surface of the printing plate, so as to form an intimateunion over the entire area, thereof.

The facing material, after being adhered to the printing plate may betrimmed around its edges, and is then vulcanized in any welllmown manneras by dipping the plate briefly in a suitable vulcanizing solution` suchas sulphur chloride in carbon tetrachloride. llf

desired, this solution may be poured over the plate. After the facinghas become cured, a coating of topping varnish, such as asphaltumvarnish, is desirably applied to the major depressed portions of theprinting plate, so

that the roller of the printing press will not contact with suchportion.

Although vents'lQ are shown in Figs. 1 and 2 for the purpose ofpermitting the escape of air which may be entrapped between the surfacelm or skin of plastic material and the preformed printing plate, it maybe desirable, under certain conditions, to vary the process of applyingpressure by the resilient cushion, as above described, in order toinsure positive and intimate contact of the surface skin at every pointon the plate. It has been found that if the pressure is withdrawn aftera short interval of time and then reapplied in the manner describedbelow in the description of Fig. 4f, that perfect contact is establishedatall points.

In Fig. 4 we have shown a conventional electrotype plate 10 whichdiffers from the printing plate elsewhere illustrated in one respectonly, Viz., it is lacking altogether in any vents for the escape oftrapped air. It is possible, however, to utilize our invention intheapplication of a-rubber facing 14 to the impression surface of such aplate. ln the accomplishment of this end a relatively light pressure isfirst applied by the resilient cush ion to the rubber facing after beingplaced over the impression surface of the printing plate. This pressureis continued for a short time onlya minute or less-and the cushion isthen withdrawn from pressure contact for a brief interval.

rllhis first application of pressure causes the facing material toconform in large measure to the irregularities in the plate, althoughthe trapped air may prevent the rubber facing from advancing the fulldistance into the depressed portions thereof, as represented in Fig. 4f.The facing sheet which is porous to some extent is rendered still moreso when stretched into conformation with the irregularities of theprinting plate, and would permit escape through the pores of the airwhich is trapped within the depressions, provided that the resilientcushion would not interfere. rfhis interference to such escape of airthrough the facing material is removed when the cushion is withdrawnmomentarily from pressure contact. The air being then re lieved, a.further and greater pressure is applied for another minute or less. Thislast pressure operation causes the facing material to advance the fulldistance into the depressions so that adherence to every point of theimpression Surface of the printing plate is assured.

Among the advantages derived from our invention are the following: Theprinting plate having a rubber facing applied to its impression surfacein the manner described. retains all of its original sharpness ofdefinition. Such a plate, or any desired num ber of duplicate plates,may be treated according to the present process, and the resultingimpression surface will be uniform in all cases. This is due in largemeasure to the fact that all operations are mechanical, and do notdepend in any degree upon the skill of the operator for the resultsobtained. The facing material is applied directly to the originalprinting plate which becomes in a single operation the finished printingplate with a facing material applied to its impression surface so as t0render the same suitable for use with inks which are water-soluble orotherwise. Due to the means employed for venting the trapped air it ispossible for the facing material to unite-with the plate at every point,including the depressed portions thereof, and Wherever the facing can beforced partly into vents (see Fig. 3) during the pressure stage apositive anchorage results therefrom. A

A printing plate so produced will take any of the commonly used oil,alcohol, or watersoluble printing inks. When Water-color inks are used,little pressure is needed to transfer the ink from the plate to thepaper. Morever, this plate will do very good vvork on poor qualities ofpaper. Due to the llght Apressure required, the plate is not Worn evenafter many thousands of impressions have been taken, and.hence does notneed to be renewed as often as is nov:r necessary with other kinds ofplates.

It will be seen, therefore, that We have provided a new and greatlyimproved plate for use in printing, particularly with watersoluble inksand also that a very simple, eficient, and economical method Ihas beenprovided for making this plate. Other methods of applying the rubber tothe face otv the plate, such as by spraying, are optional, and asalready suggested, the porosity of 'the rubber sheet, instead of ventsin the plate, may be taken advantage of to permit escape of theentrapped air. y

While We have shown and described but a single embodiment of ourinvention, it is to be understood that it is capable of manymodifications. Changes, therefore, in the construction and arrangementwhich do not depart from thel spirit of the invention may be made withinthe scope vof the appended claims. i

We claim: l f

1. A printing plate having relatively high and low portions definingimpression characters all joined integrally with vents leading tocertain ofthe low portions, and a wa- Y used in printing oil-solubleinks a thin sheet ter receptive facing adhered to the plate at everypoint over its printing surface and entering the vents therein.

2. The process of making plates for 'use with water-color inksconsisting in securing to the printing surface of a plate of the type ofwater receptive material while held under tension.

3. The process of making plates for use with Water color inks consistingof covering the printing surface of a plate of the t e used in printingoil-soluble inks with a thm surface layer of unvulcanized rubber,resiliently pressing said rubber covering intimately into contact withthe printing surfaces of said plate to impose a surface skin thereon,and vulcanizing said surface skin.

4. The process of making plates consisting of covering the printingsurface of a plate of the type used in printing oil-soluble inks with athinsurface of unvulcanized rubber, pressing said rubber coveringintimately into contact with the printing surfaces of said plate,relieving the depressed portions of the plate so as to prevent theformation of air bubbles under the sheet of rubber, and vulcanizing saidrubber covering.

5. The process of making plates consisting of covering the printingsurface of a plate of the type used in printing oil-soluble inks with athin surface'of unvulcanized rubber, pressing said rubber coveringintimately into contact with the printing surfaces of said plate,previously forming holes in the depressed portions of the plate so as toprevent the formation of air bubbles under the sheet of rubber, andvulcanizing said rubber covermg.

6. The process of making plates for use with Water color inks consistingof covering the impression surface of a plate of the type used inprinting oil-soluble inks vvithy a thin facing of unvulcanized rubber,and pressing a plurality of sheets of laminated rubber against saidrubber facing to force'it intimately around the edges of the printingsurface of said plate to conform it intimately to the impression surfaceof the plate.

7 The process of making plates consisting of covering the impressionsurface of a plate of the type used in printing oil-soluble lnks Withathin facing of unvulcanized rubber, pressing a plurality of sheets ofrubber against said rubber facing to conform it intimately to theimpression surface of said plate, and vulcanizing said rubber covering,said sheets being lubricated relative to each other and to the rubberfacing.

8. The process of making plates for use with Water color inks consistingof covering the impression surface of a plate of the type used inprinting oil-soluble inks With a thin ally slidable constituents againstsaid rubber facing to force it intimatel around the edges of theprinting surfaces ofysa-id plate.

10. The process of applying an elastic facing material to the impressionsurface of a printing plate which consists in spreading an adhesive oversuch impression surface, in laying the elastic facing material over theadhesive-treated impression surface, in placing a resilient cushionagainst the outer surface of the facing material, and in pressing thecushion against the facing material to impose a surface skin at everypoint over the impression surface of the printing plate.

11. The process of applying an elastic facing material to the impressionsurface of a printing plate which consists in spreading an adhesive oversuch impression surface, in laying the elastic facing material over theadhesive-treated impression surface, in placing a resilient cushionagainst the outer surface of the facing material and in pressing thefacing material against the impression surface through the medium of aresilient cushion having elastic laminations freely slidable relative toeach other whereby to shift as required in congruity with stretching ofthe facing material as it conforms to the varying elevations in theimpression surface of the printing plate.

12. The process of applying a facing material to the adhesive-treatedimpression surface of a printing plate which consists in pressingagainst the facing material a resilient cushion having ay contact facewhich is slidable relative to the facing material and to the body of thecushion.

13. The process of applying an elastic pervious facing material to theimpression surface of a printing plate which consists first in pressingthe material into the depressions of the impression surface, inwithdrawing the.

pressure to permit escape of the air which is entrapped and compressedbetween it and the printing plate, and thereafter in again pressing thematerial this time to the full depth of the de ressions in theimpression surface.

14. he method of making printing medium, comprising forming the image tobe printed on a hard late, and thereafter securing a thin skin oi)water-receptive material while held under tension upon the surface ofthe plate bearin the image so that the resulting surface con ormsdirectly to that of the plate.

In testimony whereof, we have hereunto set our hands this 17th day ofNovember, 1928.

. JAMES T. SIMLIS.

GEO. A. SIMMS.

